Fix disk layout

playbook.yml

---
- hosts: all
  gather_facts: yes
  vars_files:
    - devstack_gate_vars.yaml
  pre_tasks:
    # Note (dmsimard)
    # If some swap is already set up, the amount is not 100% accurate
    # (ex: 8191MB swap for a 8192MB file)
    - name: Configure swap
      include_role:
        name: "configure_swap"
      when: ansible_memory_mb['swap']['total'] | int + 10 <= SWAP_SIZE
  roles:
    - gather_host_info
    - fix_etc_hosts
    - create_base_folder
    - start_fresh_logging
    - setup_stack_user
    - setup_tempest_user
    - copy_mirror_config
    - network_sanity_check

tasks_main.yml

- name: Set ephemeral device if /dev/xvde exists
  set_fact:
    ephemeral_device: "/dev/xvde"
  when: "/dev/xvde" in ansible_devices

- block:
  when: ephemeral_device is undefined
    # TODO: Add the filesystem label to ansible_mounts fact
    # i.e, https://github.com/ansible/ansible/blob/7b73ee0818a4fa3b3155b45deb8f60e8b7a72cdf/lib/ansible/module_utils/facts/hardware/linux.py#L332
    - name: Look if ephemeral0 device exists
      command: blkid
      register: blkid

    - name: Set ephemeral device if ephemeral0 exists
      set_fact:
        ephemeral_device: "{{ lookup('pipe', 'blkid -L ephemeral0') }}"
      when: "ephemeral0" in blkd.stdout

- block:
  when: ephemeral device is defined
  vars:
    swap_partition: "{{ ephemeral_device }}1"
    lvm_partition: "{{ ephemeral_device }}2"
    opt_partition: "{{ ephemeral_device }}3"

    - name: Ensure the ephemeral device is unmounted
      mount:
        name: "{{ ephemeral_device }}"
        state: unmounted

    # [...]

I want to configure swap using disk where lvm module will create swap vm conditional. Lets say swap vol would be 2x memory when memory is <=4G, 1x memory from 4G-16G and 16G when memory is > 16G. What are your suggestions.